Homeostasis

1. Homeostasis

3. …..Homeostasis - Ability to maintain stable, favorable internalconditions even though there are changes in the external environment. Required components for maintaining stable conditions (fig. 1.4)

4. Types of homeostatic control systems Negative Feedback brings conditionback to normal level

5. Blood Calcium Homeostasis Calcitonin released in response to HIGH blood Ca. PTH released in response to LOW blood Ca.

6. Types of homeostatic control systems Positive Feedback takes condition further fromnormal

7. The Integumentary System(covering) Your Own Personal Raincoat Guaranteed to last for life! Waterproof, stretchable, washable, if damaged can repair itself  • Largest organ • Weighs 9 -11 pounds • Average 1-2 mm thick (ranges 1.5 – 4 mm)

8. Functions Protection = barrier A. chemical barrier a. bacteriocides& acids inhibit microbial growth b. melanin prevents UV light from damaging DNA c. lipids prevent dehydration & make us waterproof d. keratin prevent abrasions, resists chemicals B. physical barrier a. tight junctions inhibit microbial entry C. biological barrier a. contains immune cells Temperature regulation = sweat & dermal blood flow Sensory reception Vitamin D production = UV light converts cholesterol to a form of vitamin D Blood reservoir ~5% of blood Excretion - waste products with sweat

9. Structure Hair shaft Dermal papillae Subpapillary vascular plexus Epidermis Papillary layer Pore Appendages of skin Dermis • Eccrine sweat gland Reticular layer • Arrector pili muscle • Sebaceous (oil) gland Hypodermis (superficial fascia) • Hair follicle Nervous structures • Hair root • Sensory nerve fiber Cutaneous vascular plexus • Pacinian corpuscle Adipose tissue • Hair follicle receptor (root hair plexus) Figure 5.1

10. Homeostatic Imbalances Burns (fig. 5.10) • first degree = only epidermis is affected should heal on own • second degree = epidermis + upper dermis is affected blisters, painful • third degree = epidermis + whole dermis affected may look white, red, or black not painful (receptors are gone) fluid loss & infection are a major concern

11. Homeostasis (cont.) Cancer (fig. 5.8) • Basal cell carcinoma = basal layer keratinocytes divide and invade dermis, usually not malignant • Squamous cell carcinoma = spiny layer keratinocytes divide tends to metastasize to lymph nodes • Malignant melanoma = cancer of melanocytesoften develops at the site of moles rapidly metastasize to lymph nodes and blood vessels, use the ABCD rule

13. The Urinary System 2 Kidneys 2 ureters bladder urethra

14. Functions of the Urinary System • Filters the blood and excretes wastes • Regulate chemical composition of blood,including pH and osmolarity • Regulates blood pressure by regulating blood volume and by producing renin 4. Produces erythropoietin • Produces calcitrol (a form of vitamin D) • Gluconeogenesis during fasting

15. Circulation (Fig 25.4)

16. Parts of a Nephron • Renal corpuscle – glomerular capsule, glomerulus • 2. Proximal convoluted tubule • 3. Loop of Henle– descending, loop, ascending • 4. Distal convoluted tubule • 5. Collecting tubule

17. Urine Formation • 3 parts of urine formation • Glomerular filtration • Tubular reabsorption (PCT & LOH) • Tubular secretion • Filtrate vs. Urine • Urine - What remains after filtrate is processed • Filtrate – everything that is reabsorbed = blood plasma • Kidneys process about 180 L (47 gal) of filtrate per day but only 1.5 L is excreted as urine (3 bottles of water!!) • The rest is reabsorbed

18. 1 - Glomerular Filtration • Occurs in Glomerular Capsule • Efficient – large surface area • & very permeable to water, solutes • Fluids and small solutesmove PASSIVELY from blood plasmainto the capsularspace • Filtration favored by • pressure gradient

19. 2. Tubular reabsorption Renal Tubule • Reclaims much of the water and useful solutes from the filtrate back into the circulatory system (about 99%) • Occurs throughout tubules, most in the proximal tubules • Amount of Ca2+depends on PTH • Amount of Na+ K depends on aldosterone • Amount of water depends on ADH • For details see table 25.1 Glucose Amino acids Vitamins Na+ K+ HCO3- Water Ca2+ Mg2+ Interstitial Fluid Peritubular capillaries

20. 2. Tubular reabsorption

21. 3. Tubular Secretion • Substances are moved from the peritubular capillaries into the filtrate for disposal • Main site is PCT (except K+) • Allows removal of waste • Helps control blood pH • Amount of K+depends on aldosterone NH4+ antibiotics H+ Urea K+ Inside Renal Tubule Interstitial Fluid Peritubular capillary

22. Dilute Urine • Atrial Natriuretic Peptide (ANP – cardiac muscle) suppresses Na+ and water reabsorption which results in lowerblood volume, bp and dilute urine

23. Concentrated Urine hypothalamussenses dehydration ↓ Pituitary releases ADH (antidiuretic hormone) ↓ Principalcells in collecting tubule become permeable to H2O ↓ Water diffuses from filtrateback to circulatory ↓ results in increasedwater in blood and concentrated urine

24. The Respiratory System Functions 1. Warm, moisten, and filter incoming air 2. pH Homeostasis 3. Vocalization 4. Olfactory reception 5. Gas Exchange……

25. Gas Exchange 02 taken up and CO2 is released Coupled to circulatory system Respiratory system responsibilities a. ventilation (air in & out of lungs) b. external respiration (gas exchange lungs – blood) Circulatory system responsibilities a. transport gases (between lungs and tissue) b. internal respiration (gas exchange blood – tissue)

26. Anatomy (fig. 22.1) conducting zone structures • nasal cavity • pharynx • larynx • trachea • bronchial tree (note: open to external world , has MALT)

27. Bronchial Tree (cont.) As you move through the bronchi deeper into lungs: • Cartilage changes from rings to plates to none • Cells of mucosal epithelium change from columnar to cubodial to simple squamous • Smooth muscle increases

28. Respiratory Zone Structures (fig. 22.8) • Respiratory bronchioles have scattered alveoli • Alveolar ducts walls made of alveoli • Alveolar sacs terminal ends, clusters of alveoli

29. Alveolar Structure (fig. 22.9) • Type I alveolar cells = simple squamous epithelium with thin basal membrane • Type II alveolar cells = secrete surfactant • Alveolar macrophages (Dust cells) = immunity • Pores = equalize pressure • Elastic fibers = allow expansion and recoil

32. Female • Make eggs • Nourish young until birth The Reproductive System Functions Male • Make sperm • Deliver sperm into female’s reproductive tract

33. Male Testes – paired, ovate, glands ~ 5 X 2.5 cm • Sperm and hormone secretion • Develop near kidneys and descend into scrotum • Scrotum hang outside the body cavity so ~ 3 cooler than body temp (required for viable sperm) • can be drawn up, by cremaster muscle when cold • If cryptoorchidism (testes have not dropped) is left untreated, cells that normally produce sperm degenerate - male is infertile.

34. Testes sperm are made inside continuous with peritoneum invaginations form septa that divide inside of testes into lobules seminiferous tubules  straight tubules  rete testes  efferent duct  ductus epididymis  ductus (vas) deferens  ejaculatory duct  urethra

36. Regulation - feedback Hypothalamus

37. Female Primary sex organ - ovaries (make eggs and hormones) Accessory - fallopian tubes, uterus, vagina, and vulva (external genitals)

38. Ovary • Paired organs laying R/L of the uterus • ~ 2X size of an almond • held in place by ovarian, suspensory, and broad ligaments

39. Ovary capsule: • Superficial - germinal epithelium (simple squamous or cuboidal) • deep - tunica albuginea (dense irregular ct) inside: • cortex with follicles and eggs in different stages of development • medulla with loose ct and vessels

40. Ovaries Oocyte – eggs – sex cells - gametes • during fetal development the cells destined to be eggs migrate from the yolk sac to the developing ovary • these eggs start meiosis & arrest in prophase I • at birth a woman has ~ 1-2 million • eggs die continually and by puberty she has ~ 250,000 • Only 300-400 will ever reach maturity

41. Recap: Error rate: as many as 20% of oocytes but only 3 to 4% of sperm have the wrong number of chromosomes.

42. Ovarian/uterine/hormonal cycle (fig. 27.19,27.20) 4 phases: menstrual, preovulation, ovulation, postovulation

43. Cycle Hierarchy of Control Hypothalamus Pituitary Ovaries Uterus Note that the ovaries also exert feedback control on the hypothalamus and pituitary

44. Hormones involved • Estrogens • Secreted by follicular cells • Functions: • Promote the development and maintenance of female reproductive structures • Increase protein anabolism, including building strong bones • Lower blood cholesterol level • Moderate levels of estrogens inhibit both the release of GnRH by the hypothalamus and secretion of LH

45. Hormones involved (cont.) • Progesterone • Secreted by cells of the corpus luteum • Function • Acts synergistically with estrogens to prepare and then maintain the endometrium for implantation of a fertilized ovum • Prepares mammary glands for milk secretion • High levels of progesterone inhibit secretion of GnRH and LH

46. Hormones involved (cont.) • Gonadotropin Releasing Hormone (GnRH) • Secreted by the hypothalamus and controls the ovarian and uterine cycles • Stimulates the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary

47. Hormones Involved (cont.) • Follicle Stimulating Hormone (FSH) • Released by anterior pituitary • Initiates follicular growth and the secretion of estrogens by the growing follicles • Luteinizing Hormone (LH) • Released by the anterior pituitary • Stimulates further development of ovarian follicles • Stimulates ovulation and then promotes the formation the corpus luteum